The effect of organic salts as a flame-retardant additive for polycarbonates (PCs) or polyester carbonates (PECs) is known and is described in, for example, U.S. Pat. No. 3,933,734, U.S. Pat. No. 3,940,366, U.S. Pat. No. 3,953,399 and U.S. Pat. No. 3,926,908 as well as U.S. Pat. No. 4,104,246.
In addition to flammability the conventional fire tests evaluate the tendency to form drips and ignite that which lies below. In order to prevent dripping, anti-dripping agents such as, for example, PTFE, are conventionally added to the PCs or PECs. When incorporating PTFE into PCs or PECs, agglomeration of the PTFE particles occurs as the compounding takes place, which results in streaking and pimpling on the surface of the molding.
U.S. Pat. No. 5,804,654, EP-A 0 899 303 and EP-A 0 822 226 describe the possibility of utilising PTFE blends in order to avoid these negative effects. Corresponding products are commercially obtainable, for example under the names Metablen A-Series, from Mitsubishi Rayon, or Blendex B449, from GE.
WO-A 01/10957 describes mixtures of PC or PEC and a PTFE blend based on an acrylate copolymer and salts. However, these mixtures show a flame-retardant effect only when the sum of the contents of salts and PTFE blend is >0.65 wt. % and the PTFE content of the PTFE blends is less than 30 wt. %. A V-0 rating is achieved in the UL Test at wall thicknesses greater than 1.6 mm.
For reasons of cost and resources, however, it is fundamentally desirable to achieve satisfactory flame-proofing using the smallest possible quantities of additives.
Proceeding from the prior art, therefore, the object was to provide a composition which makes possible a satisfactory flame-retardant effect while using small quantities of additives.